Cast alloy wheels have been increasing in market share for many years. Cast alloys provide both weight reduction and unique appearance not available to old style steel wheels decorated with hubcaps. Various methods for providing a durable and aesthetically pleasing coating to cast alloy wheels have varied widely. Early versions of cast alloy wheels were coated with lacquer paint, which provided aesthetically pleasing qualities, but did not provide necessary durability. Later generations of cast alloy wheels were coated with multi-layer paint systems that included primers, colorization or base coats, and a clear coat to provide a high level of gloss to the alloy wheel. In some instances, the paint coatings are removed so that the substrate of the cast alloy is exposed to achieve a unique, “bright metallic surface” over which a clear coat is applied.
Later generations of cast alloy wheels have been provided with a metallic finish without requiring significant machining to provide a metallic aesthetic by exposing the cast alloy substrate. One such example is the use of physical vapor deposition (PVD) used to apply various alloys and metals such as, for example, aluminum, chromium, titanium, silver, nickel, and even gold over one or more layers of paint or primer that are applied to the substrate to provide a sufficiently smooth surface to receive the PVD metal coat. PVD processes have been used to coat wheels and are disclosed in U.S. Pat. No. 5,656,335, the contents of which are enclosed herein by reference.
However, consumers of vehicles having cast alloy wheels demand ever-improving and unique aesthetic qualities, such as, for example, two-tone or even multi-tone appearance providing various colors to the visible surface of the cast alloy wheel. Therefore, it would be desirable to provide a two-tone appearance to a cast alloy wheel while still making use of the desirable qualities provided by PVD coatings not presently available.